Heartfell- Mein Herz Brennt
by Blake Aster
Summary: Now, dear children, pay attention I am the voice from the pillow I have brought you something I ripped it from my chest With this heart I have the power To blackmail the eyelids I sing until the day awakes A bright light on the heavens My heart burns Will post warnings at beginning of chapters. However, biggest one is Non-Con, non-explicit.
1. Prologue

**This is the rewrite for my Underfell series! I hope it doesn't disappoint! If you see any errors, let me know! And if you've read the original, let me know how you think this compares to the original! Or not. You don't have to if you don't want...**

 **Anyways, this is just the Prologue with the lyrics to the song that I named this fic after. The real first chapter will be posted tomorrow.**

xxx

Now, dear children, pay attention

I am the voice from the pillow

I have brought you something

I ripped it from my chest

With this heart I have the power

To blackmail the eyelids

I sing until the day awakes

A bright light on the heavens

My heart burns

They come to you in the night

Demons, ghosts, black fairies

They creep out of the cellar shaft

And will look under your bedding

Now, dear children, pay attention

I am the voice from the pillow

I have brought you something

A bright light on the heavens

My heart burns

They come to you in the night

And steal your small hot tears

They wait until the moon awakes

And put them in my cold veins

Now, dear children, pay attention

I am the voice from the pillow

I sing until the day awakes

A bright light on the heavens

My heart burns

Mein Herz Brennt (Piano Version)

By: Rammstein


	2. Chapter 1

**And here is the promised first chapter! I triple checked it for mistakes and grammar, but let me know if you see anything I missed!**

xxx

Unlike humans, monsters remember everything from the moment they first opened their eyes. The first person they saw was always the most important, as they would form an attachment to that person almost immediately. It was fitting then that the first thing ever they saw was their twin. They couldn't focus long, but they saw enough to see the white body next to him, looking back with red eyes. Their hands were clasped together with what little strength their fragile bodies could muster. Their soul leapt with joy, and the soul next to them responded in kind. They were so tired now. Their eyes began to droop. It was okay. They weren't alone. Their other half was with them.

They drifted off into slumber.

Xxxx

W. D. Gaster glared at the dust on the bed with disdain. He was a tall monster, well, as tall as a skeleton monster got which was not very tall at all compared to monsters like Asgore or any of the other larger monsters. He was dressed in a black suit under a red lab coat that was certainly not protocol, but he was in a position where no one could tell him 'no.' Well, besides the King, but Asgore did not care about such things. The skeleton has many scars on his skull, all of which had been afflicted by said King. Not a one was because of his coat.

But that was not important. No, what was important was that his research was in jeopardy. Why? Because the only other adult skeleton monster left in the underground was now dust. All the trouble he went through to convince Asgore to give all those skeleton monsters to him just so that they could all end up as failures. This last one was his only chance to create more. He had planned on having several more subjects for his experiments, but now it was impossible.

At least they had born twins.

He looked down at the two monster newborns. They lay on the table, their tiny hands clinging to each other as they slept. How… nauseating. He opened the stat window on the larger. They were at least promising. They had high base stats for only LV. 0. What should he name this one? Or should he name them at all? Most skeleton monsters waited until they were older, or gave them unisex names. Skeleton monsters were one of the few genderless species of monster after all. Perhaps as they grew older, they might gravitate towards one or the other, or none at all. Perhaps he'll just number them. He had considered naming them as they were hi- no. Names were not important for what he had intended for them. Names would just get in the way. They were born to be weapons, nothing more.

He switched to the smaller one. Gaster frowned in frustration. 1 HP? Even the weakest of monsters started with at least 10. What good was this thing to him? They wouldn't last the first injection!

No, no, he couldn't give up just yet. He'd see how long the infant lasted. If either of them survived long enough, he could use them to produce more test subjects. The tiny infant may be weak, but did survive the determination injections within the womb. Perhaps there was a chance that they weren't a complete failure.

In the meantime, it was time to begin. He walked over to a small table, where there were two syringes he had prepared in advance. The fluid within both glowed with an ominous red light. He picked one up and reached for the smaller. They began to cry the moment they sensed that they were being separated from their twin. The other began to cry as well moments after. Gaster considered trying to shush them, but he decided it was something he was going to get used to. His experiments would be far front painless after all. Gaster placed the infant on the operating table. Now was the moment of truth. He pressed the needle into the newborn's soul and injected him with DETERMINATION.

The reaction was instantaneous. His bones began to glow with a dark red light. His soul- so small and fragile within his chest- pulsed with the same light. Gaster thought that their cries were bad before, but it was nearly intolerable now. Gaster was surprised by the difference between the two different cries. The cries of pain they emitted were almost enough to elicit an emotional response from Gaster.

Almost.

It took almost an hour for the screams to stop. The other infant had been trying the entire time as well. It must have been scared by the other's scream. Gaster had begun to suspect that the newborn would not survive the first injection. However, eventually the screams began to fade into whimpers and the light began to dim.

"It appears you are not as weak as I thought you were," he said. Yes, this one may prove useful. They may never become the weapon he desired, but perhaps he could use them for another purpose… But now was not the time to get lost in thought. He had time to reevaluate his plans later. He picked up the other syringe.

He had other business to attend to.


	3. Chapter 2

**I thought I'd put in a little bit of cute before we descend into hell. Again, please let me know if you see any errors I missed.**  
 **If you haven't already, I would suggest listening to the song I named this fic after, specifically the piano version. I think it sets the tone for this story- not thus chapter but the rest of it**.

Xxx

Waterfall was not an easy place to live. Not that anywhere else in the Underground was much better, but Waterfall was the second most dangerous after Hotland. It wasn't because of anything about Waterfall itself, but rather the monsters who lived there. There didn't seem to be anywhere for a rare peaceful or a weak monster to hide. The other monsters would always find you.

The most feared, however, where the ghost monsters. The incorporeal monsters that not even the King had the power to kill. They may not have high attack power, but their near immortality meant that all they had to do was outlast the other monsters. It was fortunate for the rest of monsterkind that the ghost monsters were also the most introverted. Even the most social of these monsters had little interest in monsters outside of their own kind. This also meant that not many saw any of these ghosts unless you were dumb enough to go knocking on their door.

There was, however, an exception.

Like all ghosts, Hapstablook didn't actually have a gender, but he preferred to be referred to as he. Which some found odd, considering his very feminine demeanor and interests. Hapstablook didn't care though. He was a violet color that was so dark it was almost black with glowing purple eyes.

Hapstablook was hated and looked down upon by most the other ghosts. The ghosts were expected to fit a certsin mold, but Hapstablook refused to be confined by what he saw as 'archiac traditions.' He was a friendly monster by nature, if a little conceited. He wanted to make friends with everyone, even if they mocked him in return. Things only got worse when his interests in humans was discovered. Nowadays, Hapstablook spent a lot of his time hiding from his cousins and their cruel words. Hapstablook felt that it was unfair. He hadn't done anything wrong. But that was the way it was in the underground.

At least he had Napstablook. The black and red ghost could have not been more different from their outgoing cousin, but they had a soft spot for Hapstablook. Despite all of Hapstablook's efforts, Napstablook remained his only friend. Even so, he did not give up. He just wanted to make life more bearable in the Underground. Was that so bad?

That day had been particularly tough on Hapstablook. He had almost succeeded in making a friend- a quiet monster named Shyren. She had attempted to dust him initially- which failed for obvious reasons- but he had almost won her over when two of his cousins appeared and chased her off. Hapstablook had lost it and screamed at them, which only made them laugh harder. He had to get away from them. From everyone.

That was how he ended up in Hotland. The other ghosts rarely, if ever, left Waterfall and it wasn't like he had any reason to fear. Hotland was not the prettiest, but it was it was a place where no one knew him and no one would bother him.

Or so he thought.

"WHOA."

Hapstablook took a breath before turning to face the source of the voice. He may not be in the best of moods, but he didn't want to ruin the chance of possibly making a friend because of it. He was surprised to see it was a monster child. A skeleton monster child no less. Most mothers did not allow their children out of the house until they were big enough to defend themselves (except for ghosts cause, you know, the ghost thing). Not only that, but skeleton monsters were ask but extinct, thanks to Gaster. No one knew any details of course, besides the fact that Asgore had sent them all, one by one, to be subjects of gaster's experiments and were never seen again. Not even the children were spared.

The child tall (by child standards) and lanky, with red eyes glowing softly in their soccets. They were dressed in a hispital gown of all things. They stared up at him with their jaw slack and eyes wide in wonder. Hapstablook chuckled.

"What? Never seen a ghost before?" he asked teasingly.

The child shook their head.

"Well, I've never seen a skeleton before either. Where did you come from?"

The child didn't answer, but continued to stare.

"It's not polite to stare," he said in the same teasing tone.

The child blushed in embarrasment.

"I-I'M SORRY! IT'S JUST THAY YOU'RE… YOU'RE SO PRETTY!"

It was Hapstablook's turn to blush. No one had ever complimented him before. It took a moment for him to reply.

"W-well you're not so bad youself! I'm sure you'll be quite the looker when you grow up!"

Oh god, was that creepy? Did that sound creepy? The child turned an even brighter red.

"IF I DO, WOULD YOU MARRY ME?" they blurted out.

Before Hapstablook could overcome his surprise, another child came running to grab the skeleton child's arm. This one was smaller, with a more rounded skull. They seemed so fragile next to the larger.

"We have to go!" the smaller hissed. Than, suddenly realizing there was someone else present, they pulled on the larger's arm protectively and fixed Hapstablook with a fierce glare, accompanied by furiously glowing red eyes.

"OH. BYE GHOST MONSTER! I'LL COME SEE YOU WHEN I GET BIGGER!" the monster child called back as his sibling (he assumed they were siblings anyway) pulled him away.

Hapstablook stared after them, dumbstruck. Was this child for real?

A sound brought his attention elsewhere. It sounded strange, liked static. He turned to see another skeleton monster behind him, this one an adult dressed in a black suit and red lab coat. If there was any doubt as to who he was before, the cold look in his eyes would have confined confirmed it. He brought his hands up and began to sign.

 _Did you see any children like myself come by here?_

Hapstablook felt a chill.

"Y-es actually. Are they yours?"

Gaster's only reply was to smile. Despite knowing that Gaster could not actually hurt him, Hapstablook felt as though he was in mortal danger. He put on his brightest smile, hoping none of his dread showed on his face.

"That went down there."

Hapstablook motioned towards the path opposite the one three children took. Gaster nodded and began to follow the path. It killed him to know that it was all he could do to help these poor creatures. Even if he himself could not be harmed, he was not powerful enough to protect anyone else.

"I hope you find them!" Hapstablook said, allowing on my the hint of sarcasm to slip into his voice.

Gaster paused for a moment, then continued on as though he hadn't said anything.


	4. Chapter 3

Gaster never gave them names. Just numbers. The smaller- and 12 minutes older- sibling he referred to as 031. The younger 032. It was a few years ago that the older had learned what the numbers meant. They were the 31st and 32nd subjects of his determination experiments.

The other 30 were dead.

They hated the numbers. Or rather, they feared what they represented. They refused to call themselves that. They only ever referred to each other as 'sibling'. It was enough for the older, but not for the younger. They insisted they needed actual names. So the younger chose them.

Sans and Papyrus.

The older didn't particularly care what they were called at the time, but it grew on them. Gaster was not happy about it at all. Sans had insisted they not tell, but Papyrus chose to tell him, and they did so proudly. The beating they received for it was the worst they had ever taken, but Papyrus would not give in. Those names were their only possessions in the entire world, and Papyrus would not give up.

The experiments themselves were not always bad. Sans loved the intellectual challenges put before them. Papyrus struggled with it. Papyrus hated how stupid they were compared to Sans. Gaster would never tell Papyrus, but it wasn't that they were stupid, Sans was just very intelligent. He had his reasons not to. He was fascinated by the angry looks Papyrus would send Sans' way when the other was excitedly giving Gaster the answer to a particularly difficult question. It seemed that Papyrus was beginning to grow an inferiority complex. Sans did not seem to notice. Gaster had to admit, he was growing to prefer the smaller child. Sans may never be the weapon he had intended, but they made up for it in other areas.

Papyrus, on the other hand, excelled at the physical challenges. Gaster didn't miss the way Papyrus seemed to be trying to show off how much better than Sans they were. When it came to combat training, however, Sans was left out for obvious reasons. Papyrus was a genius when it came to these most of all. They seemed to put forth extra effort in this area, enough to make Gaster suspicious. It didn't take long for him to find out why.

Papyrus wanted to be strong enough to protect Sans and one day escape. It was quite the conundrum. If he stopped teached Papyrus to fight, it would defeat the purpose of creating them. If they were going to be the perfect weapon against the humans, Papyrus needed to know how to fight. On the other hand, it was only a matter of when- not if- Papyrus would over power him.

The worst was always the injections. Gaster had been giving them higher and higher doses over the years, therefore increasing the pain. Unfortunately, there was no 'getting used to' the effects of DETERMINATION being injected into one's soul. There was no way to dampen the pain. There were times he wondered if their souls would give out under the strain.

For Sans, however, the one they hated most was the one they didn't understand.

Gaster would put them to sleep with anesthesia for this one. They had no idea what he was doing, but when Sans woke up they always felt… wrong. Like they weren't all them anymore. Papyrus never noticed this. Papyrus was just happy that they didn't get any injections on those days. But Sans knew something was wrong. It started out with small changes in Papyrus' behavior. His sibling grew more aggressive and quicker to snap. Sans himself began to notice that it was beginning to be harder to let go of their anger. Sans and Papyrus began to argue more and more.

It got worse as they got closer to hitting puberty. It began when they both decide that they preferred to be referred to as 'he'. 'Sibling' became 'brother'. It was then that Gaster decided it was time for the next phase of his experiment. He brought them into a room that was completely empty except for the surprise in the corner of the room.

It was a monster.

The rabbit-like monster was tie in the corner with duct tape over his mouth. He was severely beaten and a quick check of his stats showed that he had only 1 HP left. Gaster locked the door behind them.

"This test will be quite simple," Gaster told them.

"What test?" Sans asked, terrified of the answer. "What's going on?"

"Sans, I want you to kill him."

Sans gaped at him in horror.

"What? No! I refuse! I won't do it!"

Gaster glared at him.

"Than you will die," Gaster answered as though it were obvious. "I have no use for a weapon that cannot fight. You need to build up your LV. This is the only way. Either you kill him, or I kill you. Right here. Right now."

Sans looked back to the shivering monster in the corner. His eyes were wide and tears spilled down his cheeks. Sans felt a rush of rage.

"No," Sans said firmly. "I refuse. Go ahead and kill me. I won't do it. I. Won't. Become. You."

Gaster frowned.

"That… is disappointing."

A Gaster Blaster appeared midair, aimed directly at Sans.

"Goodbye."

The scream that followed would haunt Sans' dreams for the rest of their life. Both looked to the monster that was once in the corner of the room, only to find a pile of ashes. A bone protruded from the middle of the pile, glowing softly red. Papyrus stood facing away from them, breathing heavily.

"P-paps?"

Papyrus took a deep breath and turned around. There was a hard, cold look in his eyes that Sans had never seen before. He took a step back fearfully.

"HE IS DEAD, AS REQUESTED."

"That he is," Gaster replied. The blaster faded away. "That is not exactly what I ordered, but I believe this will do. You should be grateful, Sans, thanks to your brother, you get to live another day."

Gaster directed Sans to the operating table in the lab while he escorted Papyrus to their room. Sans sat in terror of what was to come next. It felt like ages before Gaster returned. There was something in his eyes that made Sans want to run and hide, but he knew that it would be futile.

"It appears that you are not fit to fulfill your intended purpose," Gaster said. "I had thought so since the beginning, so I decided I would use this as a sort of final test, before I repurposed you."

Sans didn't like the sound of that. Gaster smirked.

"I have to say despite it all, I do not mind this outcome."

Xxx

It was several hours before sans was returned to their room. It only contained two cots and a mirror. Tears streamed down his face as he limped through the door. He sobbed when he realized that the two cots, which had always been pushed together, were now separated. Papyrus was asleep on his which he had pushed to the corner of the room. He slept facing the wall, with the only pillow and blanket. Sans' own cot was bare.

Sans couldn't even bring himself to walk over to his cot. As soon as the door had closed behind him, Sans fell to his knees. He didn't make any noise and he wrapped his arms around himself and cried. Why didn't Papyrus just let Gaster kill him? It would have been better than… better than… this!

His soul throbbed.

It was a strange sensation. It wasn't necessarily a bad sensation, but after what had just happened, it did worry him. He clenched a fist into his gown above his soul, but was too afraid to look. He considered waking Papyrus, but was too ashamed. He began to stand with the intention of sleeping with the hope that he would never wake up, but froze. Something in the mirror caught his eye.

There was someone in their room!

Sans gasped! It was a human, of that much he was certain. He also suspected that it was female. She was a few years younger than him, if he had to guess. She was wearing a matching shirt and pants which were blue with little yellow flowers. Her feet were bare. She had tanned skin and dark brown hair. Her eyes were dark brown and almond shaped.

The girl seemed just as surprised as he was. She tilted her head as she looked at him, her eyebrows furrowed. She brought a hand up, facing him with her hand open. Sans walked towards her. It wasn't until he was standing right in front of the mirror that he realized that she seemed to be inside the mirror. Without thinking about it, he brought his hand up and pressed it against where her's was.

They both looked at their hands, then back at each other. Sans was surprised to see that she was shorter than he was, if only by a bit. He'd never met someone smaller than he was, not that he'd met anyone outside Gaster and his brother. Or that ghost they had met when they managed to escape for a few hours. Then the girl did something that took his breath away.

She smiled.

Sans stared at her, mystified. She was the most beautiful thing he had ever seen, even if she was just a figment of his imagination. She moved her lips like she was saying something, but he couldn't hear anything.

"I can't hear you," he said softly, hoping that Papyrus wouldn't wake.

He doubt she heard him, but she seemed to understand. She pouted sadly. She turned away, as if looking at something he couldn't see. She looked back and gave him an apologetic look before walking out of sight. Sans quickly pressed himself against the mirror, as though he could see where she had gone. But it was hopeless.

She was gone.


	5. Chapter 4

"Humans are the reason we are down here. They are the ones that turned on us."

Sans was barely listening as Gaster continued with his usual rant about humans. Gaster always spoke with such hatred when talking about them. It was one of the few times Gaster displayed any emotion. For a long time, Sans had believed that humans were evil, heartless creatures that deserved to be eradicated. Now be was beginning to have second thoughts.

As Gaster ranted, Sans' mind wandered to the girl in the mirror. She had appeared to him almost every night since she first appeared. Despite not being able to speak to each other, they found other ways to communicate. They had tried writing, but the humans had a different written language. So instead, they drew pictures. Her pictures were a lot better than his. One day she drew a pictures of her and two larger humans. It took a moment for him to realize what the other humans were. They were her parents. They were all holding hands and smiling. Then she pointed to him.

Sans hesitated. He looked down at the paper before him. What should he draw? Without putting a lot of thought into it, he began to draw himself. In real life, he was always smiling, not because he wanted to but because that was how he made. In the picture he was frowning. Then he drew Papyrus. A while ago, he would have drawn them holding hands like the human and her parents. Now, he drew him of to the side with his arms crossed, frowning, and glaring.

Sans almost didn't draw Gaster. He may have sired them, but he did not care for them the way the human's parents seemed to. However, it seemed dishonest to leave him out. So he drew him. He drew him with all the pent up anger inside him. He used almost all the black marker on him. By the time he was done, his Gaster was barely more than a black blob with an evil face. He looked at the picture for a moment and added one final detail before showing it to her.

He kept his eyes on his lap. He was too ashamed and afraid too see her reaction. However, after a few silent minutes, he worked up the courage to look up. He wasn't sure what he expected, but this wasn't it. She was… crying. He felt terrible. How could he make such a beautiful thing cry? She had her hands pressed against the mirror. As always, Sans pressed his own against it. She seemed to sob before pressing her forehead against the glass. He hesitantly did the same. He closed his eyes. His soul still ached, but for the first time in a long time, he felt like he wasn't alone.

"Am I boring you, Sans?"

Gaster's sickeningly sweet voice drew his attention back to the present. Gaster was looking down at him with a soft smile that was deceptively kind. That smile did not reach his eyes. For a moment, Sans was too afraid to respond. Gaster placed a hand on Sans' shoulder.

"Do not be ashamed. For ones as intelligent as ourselves, these kind of lessons can be very dull. But this is important. Try to pay attention for me," Gaster asked. Gaster's hand was now gently rubbing Sans' back. Sans felt sick.

There was a sickening cracking sound and the hand was gone. Sans looked up to see a bone lodged into Gaster's arm. Gaster observed it with a smirk then looked across the room. Papyrus had stood from his chair and was glaring at Gaster with glowing red eyes.

"DO. NOT. TOUCH. HIM."

Gaster looked like he was suppressing a laugh.

"And why should I do as you say?"

"HE IS _MY_ BROTHER. HE. IS. MINE!"

Gaster chuckled.

"We'll see about that."

Sans watched in horror as his brother was lifted into the air by an invisible force. Papyrus screeched in rage, but there was nothing that could free him front Gaster's hold. Gaster dragged Papyrus out of the room and to the lab, Sans trailing behind.

When they arrived, Gaster dropped Papyrus onto the operating table and strapped him down. Sans watched in terror, knowing there was nothing he could do to stop whatever was going to happen next. Gaster walked over to the cabinet that contained the DETERMINATION and took out a bottle. As Sans watched him prepare the injection, he realized with horror what he was going to do. Gaster filled the syringe to the brim, more than twice the amount either had received.

"Y-you can't!" Sans cried.

Gaster paused.

"Oh?"

"You'll kill him!" Sans pleaded. "Please, let him go! He won't do it again!"

"But I think he will. He has always had a rebellious streak. Someone needs to be punished for disrespecting me."

"Then punish me!" Sans said without thinking. He surprised himself, but found he didn't regret them. Gaster's eyes hardened.

"Fine."

Sans remained perfectly still as Gaster approached. Gaster didn't even bother with putting him on the other table. He undid the gown in order to gain access to Sans' soul and knelt down before Sans. Sans stared straight ahead. He wanted to pretend like he was brave, but his shaking bones betrayed him. Gaster prepared to begin the injection, but stopped. Confused, Sans finally looked at Gaster. Sans didn't like what he saw. Whatever Gaster saw had made him very pleased. Gaster met his eyes and smirked.

"Congratulations," he said. "You're going to be a parent."


	6. Chapter 5

Sans had grown into the habit of staring at his soul in the mirror when the human wasn't there. He only did so when he was alone. As much as he loved his brother, he was afraid of who he was becoming. It seemed like he was becoming more and more violent by the day. This became especially evident when Gaster would drag in some poor monster so Papyrus could build up his LV. To begin with, he did so reluctantly. Now, Papyrus did so joyfully. He didn't even bother to hide how much so. Sans had his suspicions as to why. The more he thought about it, the more he was convinced that Gaster was messing with their minds when he put them under.

But that was not what he was thinking about now. His thoughts were entirely focused on the tiny, almost imperceptible soul growing within his own. It was a strange feeling. He had felt it before Gaster had told him, although he had not known what it meant. He could feel its presence within his soul. Part of him thought that maybe he should be disgusted. This was _that man's_ child after all, but he was surprised to find he didn't care. How could he? This little soul was the purest thing he had ever seen. As beautiful as the human in the mirror. Almost more so.

He hoped this one would survive.

This would be the fifth. The first four did not survive past the first month. It was a painful experience, not physically, but emotionally. It was so easy- too easy- for him to become attached to these little souls and he grieved for each of them. It had to have been the injections. Gaster no longer injected them into Sans' soul, but rather directly into the unborn child's. Gaster claimed otherwise.

"DETERMINATION is only lethal to unborn children if I start the injections after the four weeks. Unfortunately, the problem appears to be your soul itself. You are practically drowning the soul in magic. They cannot handle it."

Sans refused to believe that. It was Gaster's fault. It had to be. Sans heard someone entering the room. He quickly pulled his gown back on and stood up. He wasn't surprised to see Gaster enter the room, but was surprised not to see Papyrus with him. He had taken Papyrus earlier for combat exercises. The very sight of the man filled Sans with rage. This must have been evident on his face because Gaster raised a brow at him.

"Do you hate me?" he asked.

Sans scoffed.

"Hate is too soft a word," Sans growled.

"Perhaps. You and your brother have suffered much pain at my hands, but it is not my fault," Gaster said.

"Not your fault? How is all of this not your fault?" Sans voice grew louder with every word. He had never defied Gaster like this. He was always too afraid. Not now. Now, all he felt was rage.

"Would you like to meet who is truly responsible?"

Sans didn't respond. Gaster motioned for him to follow. For a moment Sans considered refusing, but knew it would be foolish. He followed obediently. Gaster led him to the battle room, where Papyrus was waiting. Papyrus met Sans' eyes for a moment then looked away. Papyrus had barely looked at him let alone spoken to him since Gaster had announced his first pregnancy. He must have found him disgusting. Sans wanted to cry everytime Papyrus looked away, but he refused to do so in front of Gaster. Gaster didn't say anything as he opened the door and motioned for them to enter.

As Sans expected, the large white room was empty except for the poor victim Gaster had captured. What was not expected was exactly who-or rather what- the victim was. He stood unbound in the center of the room wearing a large hat Sans had never seen before and something in his hand that looked like a gun. Sans had never seen one before, but compared to the pictures he'd seen in books it seemed a bit fake. But that wasn't what shocked Sans. This new guy was not a monster.

He was human.

"You want someone to blame?" Gaster asked. He spoke so both could hear but Sans knew he was talking to him. "Than blame him. Blame all the humans. If they had never locked us up down here, none of this would be necessary. If they hadn't betrayed us, you would be living happily on the surface. I may have done terrible things, but they were the ones who made me- who made _all_ monsters this way."

"What 'cha buzzin' 'bout over there?" the human asked. "Do any of ya'll actually talk like regular folk? You sound like a broken radio or somethin'."

"SHUT YOUR MOUTH HUMAN!" Papyrus snapped.

Sans saw the anger in his eyes. Obviously, his brother was buying into Gaster's hate speech. Sans wasn't so sure. The human in the mirror was nothing like the evil Gaster described. Out of curiosity, Sans checked the human's stats. Only LV 2. Papyrus and Gaster were higher than that.

"Sans, the human cannot understand me, nor does he know sign language. I need you to translate for me."

Sans' and Papyrus' eyes went wide as Gaster spoke. A twisted smile spread across Papyrus' face as he stepped towards the human. The human took a few steps back.

"Whoa there. What are you doin'? What did that skele-ghost lookin' guy say?"

"You two will fight to the death. Whoever wins, goes free," Sans said.

The human's eyes went wide.

"H-Hey now! There's no need for all th-"

The human almost didn't see Papyrus' first attack coming. He dodged just in time.

"Come on! I didn't do anything wrong! All I've done is defend myself!"

"SHUT UP AND DIE!"

Sans looked away.

"Don't look away. You must watch and accept the one thing you've refused to see," Gaster said.

"And what would that be?" Sans growled.

"In this world, it's _D."_

Sans reluctantly looked back to the fight

The human was good. Papyrus was struggling to hit him. Sans began to worry. Papyrus' attack was higher, so when he did land a hit, he hit hard. But the human was fast and far more accurate as he chipped away at Papyrus' HP. Papyrus grew more and more furious as time went on. He was getting sloppier. Sans watched in horror as he hit only 1 HP. That was it. One more hit and he was finished. Unable to stand, Papyrus was on his knees before the human. The human raised his weapon with a pained expression on his face.

"I'm sorry."

Sans didn't think, he reacted. Without a single warning, not one but several Gaster Blasters appeared. The human was surrounded. Sans may have only had 1 ATTACK, but there was no way the human could survive direct hits from all of them. And hit they all did. The human didn't even get the chance to dodge.

It wasn't until he felt his LV go up that he realized what he had done. He stared in horror at the body in the middle of the room. He didn't turn into dust like monsters, which was somehow so much worse. Sans took a step back, running into Gaster. Gaster looked down at him proudly.

"Good job, son."

Xxx

Sans had the room to himself that night. Papyrus was still in the recovery room. He sat in the middle of the room. He hugged his knees to his chest as he stared at the mirror. He needed to see her. He had to. She was the only thing that made waking up everyday worthwhile. She would make everything okay. Sans nearly wept when she finally appeared. She was as beautiful as ever and greeted him with a bright smile.

Sans froze.

What was he doing? How could he look at her after what he had done? He'd killed. He killed a _human. He was a killer now._ What would she do if she knew? Would she ever want to see him again? Of course not. The humans weren't evil.

The monsters were.

Sans buried his face in his knees. He was too ashamed to look at her any longer.

"I'm sorry," he sobbed. "I'm sorry, I'm sorry, I'm sorry."


	7. Chapter 7

"Your pregnancy is moving along well. This is the longest one so far."

Sans sat on the medical bed, impatient for the exam to end. It was nearly time for bed, which meant that human would be waiting for him. She was all he could think about these days. Just seeing her was enough to make everything okay, even if he knew they never would be. He never told her, or rather showed her, the things he'd done or been through. She did not know about the child or about the human he killed. He couldn't let her know. She was the one thing he didn't want to lose because of Gaster. She was his angel.

Gaster placed a gentle hand Sans' thigh. He'd been touching Sans more and more as time passed. He hadn't done… _that_ since he'd been pregnant, but only because the child couldn't handle it. Too much magic was exchanged. Sans could tell he wanted to though.

"Come along now, my son. It is time for bed."

My son. Sans would rather he kept touching him that call him _that._ He never spoke to Papyrus that way. He hated how kind Gaster was (or at least pretended to be) to him. It was almost like the sick bastard had actually grown emotionally attached to Sans. That made Sans more sick than anything else. Sans jumped off the table and obediently went with him. Gaster kept a hand on Sans' back as he escorted him. Sans itched with the urge to break that hand, but he restrained himself. Everything would be better soon. Soon he would see his angel again.

As usual, Papyrus was asleep when they arrived. He'd been sent ahead after his daily injection. Gaster had been working him more and more physically as he got bigger, leaving him completely drained by the time they were done. Sans didn't mind. It meant that Papyrus wouldn't notice him talking to his angel. Sans wondered if Papyrus was still angry, then sighed. Of course Papyrus was still angry. Gaster, predictably, did not keep his word to release him. Gaster never admitted to breaking anything, saying that the deal was if Papyrus killed the human, not Sans. Papyrus blamed Sans, despite the fact that his brother had saved his life.

She was already waiting for him when the door opened. Sans had to force himself not to smile. Gaster and Papyrus couldn't see her, furthering Sans belief that she was just a figment of his imagination. Sans really didn't care at that point. He waited until the door closed behind him to dart forward. For the next couple of hours, he let all of his pain slip away.

Xxx

Gaster watched the screen before him. In it, Sans was staring at the mirror. He watched as the skeleton drew a picture and showed it to the mirror, as if someone was there. Gaster frowned and glared at the screen as if it offended him. He had feared the worse when Papyrus had told him about Sans' nightly activities. He placed a hidden camera in the room, hoping that he was wrong. He wasn't. It was just as he had feared.

He could not let this continue.

Xxx

Sans stood beside operating table, holding Papyrus' hand as he screamed in pain. He was retrained to keep himself front hurting himself as the DETERMINATION tortured his soul. Today was the biggest injection thus far. The red glow emanating front him was harsher than ever. Tears streamed down Papyrus' face as he begged and pleaded for it to end.

"KILL ME! PLEASE JUST KILL ME! I CAN'T- I CAN'T- MAKE IT STOP!"

Gaster was nowhere to be seen. He had disappeared about an hour ago; two hours after he had performed the injection. Sans wish he would return. He had never been so terrified. Papyrus had never reacted like this before, nor had it ever lasted this long. Tears streamed down his face when he realized he very well may have been losing his brother.

"You- you have to hold on," Sans sobbed. "P-please. You can't- you can't leave me, okay? I'm right here."

Sans released his hand, which caused Papyrus to cry louder.

"DON'T LEAVE ME!" Papyrus screamed at the top of his lungs. "DON'T LEAVE ME ALONE!"

"I'm not leaving, Paps. I'm not," Sans promised as he climbed up onto the bed. It was awkward, but Sans managed to lay next to his brother on the bed. He wrapped his arms around his body, which was shaking violently. Sans sobbed and pressed his neck into Papyrus' neck.

"Don't leave me," sans whispered into his neck. He repeated the words into his neck like a mantra. He lost track of time as they laid there. Sans almost didn't notice when the glowing began to dim. Still, he refused to let go until Papyrus' screams turned into quiet sobs and he shook front exhaustion and not from pain. Sans lifted himself up onto his elbow so he could meet Papyrus' eyes. He was conscious, but just barely. Sans placed a gentle hand on his cheekbone and Papyrus pressed lightly into his hand.

Sans jumped when he heard the door open behind him. He practically leapt of the bed to turn and fix Gaster with a furious glare. Gaster raised a brow at him and ignored him as he walked over to the bed. Sans' eyes never left him as he examined Papyrus.

"Your brother will remain here tonight," Gaster said. "I'll need to keep him under observation. I will take you to your room."

"I'm staying here," Sans said firmly. Gaster looked up at him.

"That is not for you to decide," Gaster said coldly.

"I am staying with my _brother,_ " Sans hissed.

Sans forced himself not to flinch when he felt Gaster grab ahold of his soul. He was lifted into the air until he was eye level with Gaster.

"I believe we all know how fond I have become of you," Gaster said, "But that does not give you the right to defy me. This will be your only warning."

Sans glared back defiantly. Gaster didn't let Sans down, but rather dragged him out of the room and down to his room. Gaster left sans go in the doorway and shoved him in. Sans suspected that Gaster would have thrown him in if he weren't concerned by his HP and the child. Sans glared at the door as it shut behind him. He was going to kill him, Sans decided. He didn't care if his angel would be disappointed. If anyone deserved to die, it was that monster.

Sans took a breath. His angel was no doubt waiting for him and he didn't want her to see him like that. It took a few minutes before he felt he was calm enough. His hands still shook, but it was manageable. He turned around.

The mirror was gone.

The scream that escaped his throat was worse than any scream that had come front Papyrus in the last few hours. He spun around the room in panic, hoping futilely that it had only been moved. He ran to the door and began to pound on the door.

"GIVE HER BACK!" he screeched. "GIVEHERBACKGIVEHERBACKGIVEHERBACK!"

He continued to screech until there were no longer any discernible words coming from him. Gaster couldn't take her away from him. He needed her. He couldn't do this without her. He screamed his rage at the door until he couldn't go on any longer and collapsed. Rage and panic blurred his vision. He was hyperventilating, despite not needing to breath (he was a skeleton after all). In his mind, there was only hatred. Hatred for him.

And that evil parasite in his chest.

His vision turned red. How dare this… this… _thing_ leech off of him, feeding off his magic. This thing that _he_ put there. This thing that was part of _him._ Hadn't _he_ taken enough front him? Fine. If it wanted his magic, it could have it. Blinded by rage, he began to channel all his magic to it. He didn't react to its distress as it began to drown in magic. He didn't care. He just wanted to be free if _him._

He felt it shatter.

It was a startlingly sudden change. One minute, he was filled with so much rage he felt like he was going to burst, the next he felt nothing. What had happened? He felt dazed. What was he doing? What did he do?

Horror filled him.

 _What did he do?_

 _Xxx_

Gaster cursed under his breath. When he removed the mirror, he could never have predicted what Sans had done. They had finally conceived a child strong enough to handle Sans' magic, only to have it end like this. On the screen, Sans' have curled into himself. His back shook as he cried-

Gaster straitened in his seat. That didn't sound like crying. He stood up quickly and went for the door. He turned the knob. The door didn't budge. He tried to push it open again. Something was blocking it from the other side. He really wished the moron who put the door in so it opened backwards was still alive so he could dust him again.


	8. Chapter 8

Papyrus collapsed against the wall. His entire body still ached. He had to hurry. He didn't know how long the cabinet was going to keep Gaster trapped. He was almost there. Just a little more. The door was just a couple more feet away. Using the wall to keep himself steady, he took the last few steps to their room. He undid the lock before pushing the door open. He barely managed to miss his brother as he fell to the ground. He groaned in pain. He struggled onto his hands and knees. He didn't have time to rest.

It was then he noticed a strange sound. Sans was laying on the floor next to him, facing the opposite direction. His back was shaking, which he'd initially thought meant that he was crying. He was wrong.

Sans was… laughing.

It was a chilling sound. There was nothing happy about it. It was manic, hysterical laughing that was steadily growing louder.

"SANS?"

Sans stopped. Papyrus raised a shaking hand and rolled his brother over. Sans didn't fight. Papyrus didn't like what he saw. He had never seen someone who was crazed before, but he imagined this was what it looked back. There was something disturbing in the way his brother's eyes stared back at him, which was made worse by the smile in his face.

"WE HAVE TO GO. NOW IS OUR CHANCE TO ESCAPE."

Sans didn't respond.

"WE'LL GET OUT OF HERE, STEAL SOULS FROM THE KING AND ESCAPE TO THE SURFACE. COME, WE DON'T HAVE TI-"

"i'm not going."

Papyrus stared at his brother in shock.

"WHAT ARE YOU TALKING ABOUT?" Papyrus growled.

"you go. i think… i think i'm going to stay here."

"LIKE HELL YOU ARE. YOU ARE COMING WITH ME AND WE ARE GETTING OUT OF HERE."

"no."

"WHY THE HELL WOULD YOU WANT TO STAY?"

"i belong here."

"WHAT ON EARTH ARE YOU GOING ON ABOUT? WHY?"

'i'm just as twisted as he is."

Sans began to laugh breathlessly. Papyrus didn't know what to do. He was too late. Gaster had broken him. No, he couldn't give up. If Gaster broke him, Papyrus would fix him. But first, he had to get his brother out of there. Before Papyrus could even begin to get to his feet, he felt a familiar, invisible hand grasp his soul. He was lifted into the hair and thrown painfully against the far fall. He kicked his feet and struggled to get free, but it was hopeless. Gaster approached swiftly. Panic set in when Papyrus met his eyes. He had never seen such rage in Gaster before.

"You are officially more trouble than you are worth," Gaster said. Papyrus froze. His eyes widened in horror as a gaster blaster materialized in the air. It began to gather energy in its mouth, preparing for the final blow.

"Goodbye."

Everything was over so suddenly, it took Papyrus a moment to realize he wasn't dead. He fell to the ground with a gasp. He looked around frantically, but he was alone. What was going on? He was certain that he was about to be killed by… killed by…

Killed by who?

Xxx

Gaster stumbled as he recovered from what was the most jarring experience in his life. He looked around in confusion. Why was he at the core? He looked around for an explanation. There was no one there, except one person. Sans stood right behind him. There was a crazed smile on his face that didn't quite reach his eyes. His eyes portrayed no emotion at all, as if they were dead.

"You… did this?" Gaster asked incredulously.

Sans shrugged.

"How… when…?"

"a while ago, although it took me forever to figure it out. i wanted to use it to escape, but i barely had the magic to teleport myself. you should have seen what happened to the pillow i teleported with," Sans chuckled, but he sounded tired. "i was kinda hoping the same would happen to you. least now i know i can take papyrus."

"You are delusional if you think I'm going to let you," Gaster growled. He barely moved a step when he felt a cold hand grip his soul. He was too surprised to react as he was lifted into the air.

"i was too afraid to fight back before. i thought i wasn't strong enough. not that i cared if you killed me, but what would happen to papyrus? looks like i didn't have to worry though. looks like i didn't know my own strength."

Gaster was swung over the core. Gaster tried to summon a blaster, although he knew it was pointless. There was no way he could gather enough magic for even the most basic of attacks while Sans had a hold of his soul.

"you know, you'd think i'd be happy. happy to finally be rid of the monster who has tormented my brother and i our entire lives, but you know what," Sans paused for a moment and fixed Gaster with a dead-eyed star. "i don't feel anything."

Gaster had expected Sans to release his hold and let him fall. He was prepared to summon a blaster to catch himself. He did not expect Sans to throw him in into the core. Gaster let out a breathless chuckle. In the end it appears his experiment was a success after all.

Xxx

They were free.

It was over.

He was gone.

These words should have filled him with joy and relief. They didn't. He began to wonder if this emptiness that filled his soul would ever go away. He took a deep breath and pushed those thoughts to the side. Papyrus needed him right now _(why would he need you? he'd be fine on his own. he's not weak like you)._ When he returned, his brother was sitting against the wall still. He seemed a bit dazed. He looked up as Sans approached.

"SANS?"

"it's over. he's gone."

Papyrus looked confused.

"WHO'S GONE?"

Sans didn't respond. Was this because he'd thrown Gaster into the core?

"WHAT HAS HAPPENED BROTHER? WHY DON'T I REMEMBER ANYTHING?"

"what do you remember?" Sans asked.

"I… MY NAME IS PAPYRUS… YOU ARE MY BROTHER SANS… BEYOND THAT I…"

Sans gently patted his shoulder.

"that's alright, bro. trust me, it's probably better this way."

Papyrus didn't seem happy with that answer, but nodded. Sans helped Papyrus get to his feet. Papyrus was still too weak to stand on his own, so he wrapped an arm around Sans' shoulders.

"you know, i think i might actually miss this place."

"I DON'T EVEN KNOW WHERE WE ARE."

"don't worry. you'll be fine. i'll be right by your side."

"PROMISE?"

"always."

A thought crossed Sans' mind.

"after all, i'd be bone-ly without you!"

Xxx

They spent the night at a place they would later know as the Garbage Dump, although they probably could have guessed that. Sans had managed to find enough old clothes and blankets to make a decent enough place to spend the night. Sans had remained at Papyrus' side until he fell asleep. Once he was certain he was safely in dreamland, Sans got up and went to find something he had seen earlier. He had been so happy to see it, he nearly wept for joy. It was a mirror. It wasn't as big as the one he was used to and it had a crack in it, but that didn't matter to him. Sans sat in front of it the entire night, waiting for his angel to appear.

…

 _But no one came._


End file.
